1. Field of the Invention
This invention relates to measuring reflectance of fossil substances such as vitrinite macerels in coal and oil-shale kerogen to determine their geological age, carbon content, fuel energy per volume and suitability for particular fuel uses. Favorableness of geological conditions for oil and gas as well as their probable composition in areas of deposits of coal and oil shale is indicated also by measurement of vitrinite and other fossil reflectance. In particular, this invention makes quick, reliable and convenient measurement of reflectance of samples of sedimentary fossil rock achievable by non-technical personnel.
2. Description of Related Art
Instrumentation suitable for accurate measurement of reflectance of vitrinite by skilled laboratory personnel and technical specialists is available in the prior art. Examples are described in "QUANTIMET 520" by Cambridge Instruments Co., "ACAS 470" by Meridian Co., and "BIOVISION" by Perceptics Co. Instrumentation described in all three of these references is for generalized use that requires specialists to operate. Neither the physical arrangement, structure, capability nor methods of using known instrumentation are suitable for operation by a generalist, by specialists skilled in other technology or by non-technical personnel. Japanese Patent Number 58-22940 likewise teaches very appropriate instrumentation for reflectance analysis of coal but requires operation by a specialist rather than by unskilled personnel. U.S. Pat. No. 4,617,682 by Mori et al describes instrumentation structured in some ways similar to parts of this invention but without modifications and working relationships of parts for use by unskilled personnel. It is structured to test for uniformity of sample materials. It would require technically-skilled personnel, rather than non-technical employees, to use it for measuring reflectance of vitrinite, kerogen and other fossil substances. Further, it would require much time and would not be sufficiently reliable nor economical for such use even by those skilled in the art to which it appertains.
Other devices less suitable yet for reflectance analysis of hard fossil deposits by non-technical personnel are described in U.S. Pat. No. 4,591,718 by Amer and U.S. Pat. No. 4,491,411 by Goldstein. The Amer patent describes a device for infrared spectroscopy. The Goldstein patent is for measuring uranium content in ores. Neither could be used effectively nor economically for measuring reflectance of vitrinite by either skilled or unskilled personnel.
Measuring reflectances of fossils is vital to modern civilization for a variety of reasons related to paleontology of fossil fuel. Algae and insects developed earlier in aeons of geological time than larger forms of plant and animal life. They were not as abundant and concentrated relative to conditions around them because there was not a habitat of other forms of life that were larger and more massive for deposit of their remains in formation of fossil materials. They are not as dense or concentrated in proportion to inorganic materials around them, even though aged longer. Consequently, there is much rock among their remains. In combination with inorganic rock, their remains form what is known as oil shale. Their organic fossil remains are known as kerogen. Kerosene was one of the first commercial products produced from their remains. Petroleum products can be obtained from heating the oil shale because of its older and more "coalified" condition with more concentrated forms of carbon. Even though old and high in carbon content, however, its reflectance is low because the algae and insects from which it was formed are not as dense as life forms that developed later. Reflectance of fossil results from carbon density. Consequently, kerogen reflectance is relatively low and difficult to measure.
Fossil remains from larger and more dense plant and animal life formed higher densities of fossil carbon materials. As they aged, their remains became liquid and seeped to lower levels as present petroleum deposits if the geological conditions of overburden were sufficiently conducive to such processing by nature. Fossil remains of the same age or of less age that were in less favorable conditions for formations of liquids formed coal or coal tars, depending on the geological conditions. Thus the nature of coal and kerogen in sedimentary conditions for fossil development can be indicative of the nature of petroleum and its likelihood of existence.
As coal ages under conditions favorable for development of coal, rather than petroleum, its volatile products diminish and its density of carbon increases. Carbon is the fundamental constituent of fossil fuel. Thus its density determines BTU's per pound of fossil fuel. BTU's per pound of coal, for instance, can range from 14,000 for grades of anthracite coal to 9,000 for grades of bituminous coal. Peat from which they develop has approximately 5,000. In addition to density of latent heat, there is also the ability of coal to swell in coke production processes for yielding various grades of coke for smelting different types of ores and scrap materials.
A fossil carbon compound known as vitrinite has a reflectance of light in proportion to density and, therefore, a reflectance which indicates the age and development of fossil fuel, particularly coal. Other types of carbon deposits known as exinites and inertinites have less reflectance. Vitrinite occurs in concentrations known further as vitrinite macerals. Between vitrinite macerals, there are less dense carbon materials and combinations of organic and inorganic materials. Measuring reflectances of vitrinite, therefore, requires measurement of not only vitrinite macerals, but also the less dense and less reflective materials between the vitrinite macerals. Some of the materials between the vitrinite macerals is resinous, less reflective and causes "noise" in electronic systems of measurement. Some types of plant and animal remains in fossil materials have more dense carbon than others.
Before the advent of measuring reflectance of vitrinite macerals and before present paleontological methods for predicting existence of oil and gas, there was a wide variety of methods for analyzing coal. All were manual and macroscopic rather than microscopic. Observable physical layering, measuring proportions of volatile matter and measuring pore space were included. It was difficult and subject to inaccuracy due to subjectivity.
Now, by measuring reflectance, analyzing fossil materials is much more accurate. But it is still fraught with difficulties, inaccuracies and high costs resulting from the nature of present equipment and methods for measuring reflectance. Exorbitant time of highly-skilled individuals is required. Fatigue causes inaccuracies. Precise standardization is lacking. The equipment is bulky and difficult to transport to areas of need.
It was to overcome difficulties and limitations of present equipment and methods for measuring reflectances of fossil material and to increase the scope of measurable fossil materials that inspired this invention.